Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/005—Heat treatment of ferrous alloys containing Mn
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B43/00—Protecting clockworks by shields or other means against external influences, e.g. magnetic fields
  • G04B43/007—Antimagnetic alloys
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/076—Use of slags or fluxes as treating agents
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/10—Handling in a vacuum
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D5/00—Heat treatments of cast-iron
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
  • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/02—Making non-ferrous alloys by melting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/04—Making ferrous alloys by melting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C37/00—Cast-iron alloys
  • C22C37/06—Cast-iron alloys containing chromium
  • C22C37/08—Cast-iron alloys containing chromium with nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/04—Oscillators acting by spring tension
  • G04B17/06—Oscillators with hairsprings, e.g. balance
  • G04B17/066—Manufacture of the spiral spring
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present invention relates to an antiferromagnetic alloy based on iron and manganese as well as its preparation process (alloying and processing).
• the invention also relates to mechanical parts composed at least in part of this antiferromagnetic alloy.
• the field of use of the present invention relates to watchmaking, in particular timepiece resonators.
• a resonator for a timepiece has the primary function of resonating invariably whatever the environment in which it is located. This is the reason why a resonator is preferably made of an élinvar material (consisting for example of 59% of iron, 36% of nickel, and 5% of chromium), that is to say that its modulus of Young (or elasticity) remains insensitive to temperature variations (Charles-Edouard Council, Nobel Prize in Physics of 1920).
• Documents EP 1 422 436 and EP 0 886 195 propose solutions making it possible to have materials which are, in addition, insensitive to magnetic fields. In general, a resonator is made from complex and expensive alloys.
• alloys whose timepiece resonators are formed generally comprise, in addition to iron and nickel, several additives such as chromium, silicon, titanium, manganese and beryllium.
• This alloy known as the Nivarox alloy, is an Elinvar alloy with a Young's modulus insensitive to temperature changes. In addition, its Young's modulus varies very slightly in the temperatures considered (-15 to -50 ° C in general) but much less than most alloys ( Figure 1).
• the Applicant has developed a new antiferromagnetic alloy based on iron and manganese remedying the problems of the prior art.
• This alloy can serve as a material for the manufacture of a timepiece resonator. Indeed, this alloy has the mechanical properties required to be able to be shaped to form a spiral spring for example, which is not the case for all the antiferromagnetic alloys (Liu et al., Acta Materialia, 2003, 51, 507-519). For this, the alloy must be drawn, rolled, rolled and have adequate elastic properties.
• the antiferromagnetic alloy according to the invention consists mainly of iron and manganese. In view of its composition and its preparation process, it provides an inexpensive alternative that can be easily implemented with respect to the materials of the prior art.
• the antiferromagnetic alloy according to the invention is free of cobalt and beryllium.
• This alloy has a hardness between 200 Hv and 400 Hv, preferably between 280 Hv and 370 Hv, which is suitable for use in the field of watchmaking.
• This alloy has a Young's modulus of between 150 GPa and 250 GPa, preferably between 160 GPa and 200 GPa, which is suitable for use in the field of horology.
• the invention also relates to a method of manufacturing this antiferromagnetic alloy and its use in the field of watchmaking, for example to manufacture a resonator for a timepiece.
• the antiferromagnetic alloy having a composition consisting of:
• the percentages are expressed by weight relative to the weight of the antiferromagnetic alloy. It is an alloy whose composition is homogeneous. The elements are therefore distributed homogeneously within the alloy.
• This alloy consists of the elements above. In other words, it does not include other elements. Thus, this alloy is free of cobalt and beryllium.
• the alloy is advantageously free of residual impurities.
• it advantageously comprises less than 1500 ppm of residual impurities, relative to its weight, more preferably less than 600 ppm.
• the ppm are expressed by weight relative to the weight of the antiferromagnetic alloy.
• the residual impurities can correspond to at least one of the following elements: silicon, carbon, sulfur, oxygen and nitrogen.
• silicon concentration does not exceed 500 ppm.
• concentration of carbon or oxygen or sulfur does not exceed 100 ppm.
• nitrogen concentration does not exceed 20 ppm.
• the manganese content is between 10% and 30% by weight, more preferably between 24.0% and 26.0% by weight, and still more preferably between 24.0 and 24.6% by weight.
• the manganese content is important because it is associated with manganese that the iron is transformed into antiferromagnetic phase. So enough is needed so that the iron is no longer ferromagnetic. On the other hand, it is useless to exceed the optimum concentration of manganese.
• the chromium content is between 4.0% and 10.0% by weight, more preferably between 6.5% and 9.0% by weight, and even more preferably between 7.0 and 9.0. % by weight, preferably between 7.3 and 8.1% by weight.
• Chromium forms a protective oxide layer in contact with air (also called a passivation layer) that prevents premature corrosion of the material. Too little chromium does not provide anti-corrosion properties.
• the nickel content is between 5.0% and 15.0% by weight, more preferably between 5.5% and 7.5% by weight, preferably between 6.3 and 6.6% by weight. .
• Nickel serves to stabilize the antimagnetic iron-manganese phase, which is stable only at temperatures above room temperature.
• the titanium content is advantageously between 0.5% and 2.0% by weight, more advantageously between 0.3% and 1.3% by weight, and even more advantageously between 0.3% by weight. % and 1.2% by weight, preferably between 0.5 and 0.8% by weight. Titanium is a hardener, it is used to obtain the mechanical properties necessary for the process of transformation of the material. On the other hand, its affinity with oxygen and nitrogen make it a pump of impurities. In other words, the presence of titanium also favors the presence of impurities. This is why its content is limited.
• the antiferromagnetic alloy consists of:
• the alloy being free from beryllium
• the antiferromagnetic alloy consists of:
• the alloy being free of beryllium
• the amount of iron is adjusted according to the embodiments and corresponds to the amount necessary to reach 100% by weight. As already indicated, the amount of impurities is advantageously less than 1500 ppm. Use of the alloy
• the antiferromagnetic alloy according to the invention is used in the field of watchmaking, in particular for the manufacture of a watch movement component.
• the present invention also relates to a watch movement component at least partly made of this antiferromagnetic alloy. It is advantageously entirely composed of this alloy.
• the watch movement component is a resonator, at least partly made of this antiferromagnetic alloy.
• the resonator consists entirely of the antiferromagnetic alloy.
• the resonator is in the form of a spiral spring, but it can also be a resonator with flexible blades, such as a tuning fork, or a virtual pivot type resonator, using to the principle of flexible guidance.
• the invention also relates to a watch movement comprising at least one of the components consisting at least in part of this antiferromagnetic alloy.
• the invention also relates to a watch comprising a watch movement of which at least one of the components comprises this antiferromagnetic alloy.
• This watch comprises at least one component at least partly made of the antiferromagnetic alloy.
• the component is a resonator and more preferably, the component is a spiral spring entirely made of the alloy according to the invention.
• the method of manufacturing the antiferromagnetic alloy according to the invention comprises at least one melting and a purification step.
• the cast iron makes it possible to form the alloy with the desired metals.
• the second cast iron makes it possible to purify the alloy by removing a maximum of impurities.
• manganese whose partial pressure of its gas is relatively high at melting temperatures of the alloy.
• the process according to the invention makes it possible to retain the same quantity of manganese before and after melting and a purification step.
• This method for producing an alloy comprising iron and manganese, and more particularly an alloy according to the invention. This process comprises in particular the following successive steps:
• the constituents of the alloy being at least iron-based and manganese-based,
• a purification step carried out in one or more stages, for removing impurities of the alloy components while limiting evaporation of manganese, and operated at a pure temperature T and a pressure P greater than the pressure atmospheric.
• the alloy has a total content of impurities of less than or equal to 1500 ppm.
• the impurities are those mentioned above.
• the purification step at the pressure P is carried out so as to limit the evaporation of the manganese.
• the variation of the manganese content resulting from the purification step operated at the pure temperature T and under pressure P does not exceed 5%.
• the method for manufacturing the antiferromagnetic alloy according to the invention comprises at least the following successive stages:
• a melting step of the constituents of the alloy for forming the alloy with the desired metals can for example be carried out in an arc furnace (in particular an electric arc furnace) or a vacuum induction melting furnace (VIM),
• step b) a melting of the alloy obtained in step a) for purifying the alloy while limiting the variation of the manganese content, in particular by limiting its evaporation by performing this step at a pressure above atmospheric pressure.
• this step can for example be carried out by a technique chosen from electro-conductive slag under pressure (PESR: pressure electro slag remelting) or in a cold crucible to allow the dissolution of impurities and inclusions. .
• PESR electro-conductive slag under pressure
• the purification step is thus carried out by a process involving reflow at a pressure greater than atmospheric pressure, advantageously an electro-conductive slag remelting process at a pressure greater than atmospheric pressure.
• the pure temperature T is between 1250 and 1450 ° C, more preferably between 1300 and 1400 ° C.
• the temperature Tf is the melting point of the alloy constituents is advantageously between 1250 ° C and 1450 ° C, more preferably between 1300 ° C and 1400 ° C.
• the purification step it is important to note that the manganese tends to evaporate rather quickly beyond a certain temperature. Since the content of the final manganese alloy is very important for obtaining certain properties of the material, it is important to resort to a process which limits its evaporation. While the evaporation depends, beyond a certain temperature, on the pressure of exposure of the material to the process, a step carried out under pressure substantially reduces the variation of the manganese concentration.
• the purification step operated at a pure temperature T according to the range stated above is advantageously carried out at a pressure P greater than 10 bar, more preferably greater than 20 bar, and still more preferably greater than 40 bar.
• the pressure P is advantageously less than or equal to 50 bar.
• the melting step is not necessarily carried out at a pressure greater than atmospheric pressure. It can in particular be carried out under vacuum for example in a vacuum induction furnace.
• this alloy In order to use this alloy in the field of watchmaking, it is fashioned according to conventional techniques. It should be noted that the process described above can also be applied without departing from the scope of the invention to any alloy comprising iron and manganese elements, including any alloy in which the manganese content had to be controlled.
• an ingot of the antiferromagnetic alloy is hot forged. Forging of the ingot is performed at a temperature below the melting temperature of the alloy, preferably less than or equal to 1100 ° C. However, the forging temperature is advantageously greater than 800 ° C. Forging makes it possible to obtain bars whose diameter is preferably between 10 mm and 40 mm, more preferably between 15 mm and 25 mm.
• Bars obtained by hot forging are then hot-rolled and cold-rolled to a diameter of 5 mm.
• the rolling is carried out after a heat treatment at a temperature preferably between 1200 ° C and 800 ° C, more preferably between 1100 ° C and 900 ° C to lower its hardness.
• the bars with a diameter of 5 mm are then cold drawn to the desired diameter, preferably of the order of 0.5 mm.
• one or more heat treatments can be implemented. These heat treatments are carried out at a temperature advantageously between 800 ° C. and 1200 ° C., more advantageously between 900 ° C. and 1100 ° C.
• the alloy can then be drawn to a final diameter advantageously less than 100 ⁇ and then rolled, wound and fixed to form a spiral spring.
• Figure 1 shows the Young's modulus of the Nivarox alloy (38 to 41% nickel, 7.8 to 8% chromium, 1% titanium, 0.2% silicon, 0.4% manganese, 0.8 to 0.9% beryllium , and iron balance) as a function of temperature.
• Figure 2 illustrates the magnetic hysteresis cycle of the same Nivarox alloy.
• FIG. 3 illustrates the evolution of the Young's modulus of an alloy according to the invention as a function of temperature, after various heat treatments.
• FIGS. 4 to 15 illustrate the magnetic hysteresis cycles of an alloy according to the invention as a function of the temperature and the heat treatment time.
• FIG. 16 is a simulation of the diagram of the distribution of the different phases of an alloy according to the invention as a function of temperature.
• Table 1 Preparation conditions of the alloys according to the invention INV-1 to INV-12.
• Figures 4 to 15 illustrate the magnetic hysteresis cycles of the alloys according to Examples INV-1 to INV-12. These alloys have the same composition according to the invention, but they have undergone different treatments. Figures 4 to 15 thus reflect magnetic hysteresis cycles as a function of temperature and heat treatment time. The influence of these two annealing factors is visible on the magnetic measurements ( Figures 4 to 15). We can also see the influence of temperature and time on the evolution of the behavior anomaly of the Young's modulus measurement as a function of temperature ( Figure 3). Magnetic measurements were performed on the examples according to the invention INV-1 to INV-12. The mass and density measured as well as the volume of the samples are given in Table 2. Table 2: mass, density and volume of the samples according to the invention
• the measurement of the magnetic moment as a function of the applied magnetic field was carried out in VSM mode (vibrating sample) with a frequency of 14 Hz and an amplitude of 3 mm.
• Magnetic hysteresis cycles were measured over five quadrants ( Figures 4 to 15), ranging from a minimum field of -2000 Oe (- 159 kA / m) to a maximum field of +2000 Oe (- + 159 kA / m), with a pitch of 20 Oe (-1592 A / m).
• FIG. 16 corresponds to a simulation illustrating the various phases of this alloy as a function of temperature, and more particularly the proportion of sigma phases (intermetallic phase), Laves phase, BCC (centered cubic) and FCC (face centered cubic) networks. ), and liquid phase.
• This diagram also gives the solidification temperature ( ⁇ 1336 ° C) and liquefaction or melting temperature (> 1383 ° C) of the alloy.

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• 2016
  • 2016-11-04 EP EP16306448.8A patent/EP3327151A1/de not_active Withdrawn
• 2017
  • 2017-11-06 EP EP17792101.2A patent/EP3535425B1/de active Active
  • 2017-11-06 US US16/343,879 patent/US20190265651A1/en not_active Abandoned
  • 2017-11-06 JP JP2019522470A patent/JP2020501006A/ja active Pending
  • 2017-11-06 CN CN201780066872.XA patent/CN109937261B/zh active Active
  • 2017-11-06 WO PCT/EP2017/078365 patent/WO2018083311A1/fr unknown

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